1. Field
Apparatuses and methods consistent with the following description relate to capturing an image, and more particularly, to generating a depth image to generate distance information.
2. Description of the Related Art
Recently, techniques for obtaining distance information of an object, including a three-dimensional (3D) camera or laser radar (LADAR) have been researched. As one of techniques for obtaining distance information of an object, a light time-of-flight measurement method is used, which measures a distance (hereinafter, referred to as a “depth”) from an image capturing apparatus to an object.
The time-of-flight measurement method primarily projects light of a particular wavelength onto an object, and measures or captures light of the same wavelength reflected from the object through a special transformation process using a photodiode or a camera. Special processing is performed to extract depth using the measurement value obtained by the photodiode or the camera. In this regard, various time-of-flight measurement methods for the above optical process procedure, that is, a series of procedures including light source projection, reflection from the object, optical modulation, capturing, and processing have been introduced.
As one example of the time-of-flight measurement methods, a shutter light pulse method projects light of a particular wavelength (e.g., far-red light of 850 nm) of an object to be captured to the object using a light emitting diode (LED) or a laser diode (LD), modulates an optical image which is reflected from the object and has the same wavelength as the initially projected light using an image intensifier or a specific modulation element, and captures an image from the optically modulated optical image using an image sensor. Then, a value measured by capturing the image through the image sensor is processed, so that depth of a point or the image is obtained.
During the above procedures, to identify a phase difference according to a distance of light or light time-to-flight, optical modulation is required to be performed at ultrahigh speed ranging from several tens of MHz to several hundreds of MHz. To this end, an image intensifier employing a multi-channel plate is used or a sold-state modulator element formed of a substance selected from a group of GaAs. Recently, a thin modulator element that uses a GaAs-based modulator element and an electro-optic substance has been employed to improve the characteristics.
Meanwhile, examples of a recently introduced method of pulse driving a light source and an optical modulator element during an optical process for depth extraction may include a method of using a particular waveform such as a triangle waveform such as a ramp waveform, a method of using a sine wave, and a method of using an intact nonlinear waveform. The above methods require a method of driving a light source and an optical modulator element and a depth extraction calculation method using a captured intensity value, which is called a depth algorithm.
In the above-described methods, when multiple users simultaneously capture an image of an object in a close distance, a disadvantage occurs in that infrared light sources projected from different cameras are generally incident to optical systems of all cameras, causing an error in a depth extraction result.